Maintenance of the proper moisture content to roots of crops is critical for successful agriculture. Too much or too little water may waste precious water or create an unsatisfactory region for the roots to thrive in, either too dry or too wet.
Farmers who irrigate for their crops have for many years used their acquired knowledge to judge how much and when water is to be added. In recent years, agriculture technology has advanced considerably in determining what plants really need. Advanced irrigation systems such as drip irrigation enable rates of water supply and application of the water which are much more effective that long-established flooding techniques.
Of considerable importance has been the development of measuring devices which measure and read-out the moisture content already in the soil so that a more precise delivery of water can be made at a time and in an amount that is really needed-no more and no less. One long-established instrument of this type is the Irrometer tensiometer product sold by Irrometer Company, Inc. Of Riverside Calif., exemplified in U.S. Pat. Nos. 4,583,925 and 5,179,347.
In the Irrometer device the read-out is derived from measurement of pressure in the instrument itself which is developed as a function of the suction demand for water by the roots. This well-known measurement is customarily read out on the dial of a rotary-reading instrument, a pressure (vacuum) gauge.
In this device, a rotary indicator (a needle) points at an adjacent dial which carries indicia respective to pressure, for example of upper and lower suitable limits, or of numbers respective to the measures pressure, or of both.
Agriculturist have long used these measurements as informative guides to set irrigation controls as appropriate. It is an object of this invention to adapt this instrument for response to the needle position of its meter, and to provide a read-out that can be visual, or electronic. When electronic the signal can be electronically recorded or can be made part of an alarm or control system.
It is another object of this invention to be readily adaptable to meters used for other measurements, such as vehicle speed and altitude, for example by the simple addition of magnetic polarity to the needle or by a magnet attached to it, and a magnetic-field responsive rotary-position detector adjacent to the dial. This device is adaptable to a “snap-on”. construction for existing instruments.